In Vitro Evaluation of Flow Distribution in All-Region Perfusion during the Norwood Operation.

Continuous all-region perfusion has the potential to reduce total body ischemia during the Norwood procedure. This technique involves placing cannulas in the innominate artery, descending aorta, and native aortic root, thus providing continuous flow to the whole body at mild hypothermia (32-34°C) during the entire operation. However, the cannulation strategy in this approach must be optimized to achieve adequate flow rates to all vascular beds. To ensure appropriate blood flow rates to three cannulas of different caliber supplied by two inflow pumps, a benchtop evaluation of comparative flow rates through branched cannulas with variable independent perfusion pressures was conducted. Two isolated vertical columns with outlets at 10 mmHg intervals to allow for adjustable perfusion pressures were filled with expired banked packed red blood cells and fresh frozen plasma. The main arterial line was bifurcated with an 8-Fr arterial cannula inserted at the base of one column and a 4-mm (outside diameter [OD]) olive tip cannula inserted at the base of the other column. Flow rates were measured on each branch of the »â€³ arterial lines. Under experimental cardiopulmonary bypass (CPB) perfusion pressures of 30-50 mmHg on the 8-Fr arterial cannula column, the branched olive tip cannula accommodated less than 25% of total flow at total flow rates of 50-700 mL/min. This fraction is insufficient to sustain adequate lower body perfusion. However, the olive tip flow fraction was found to be sufficient for coronary blood flow (5-20 mL/kg/min) when olive tip perfusion pressures close to average neonatal diastolic blood pressures (20-60 mmHg) were tested. For all-region perfusion during the Norwood operation, primary CPB arterial flow should be divided to the head and coronary circulation with an independent pump delivering flow to the descending aorta. This should avoid cerebral over-circulation and insufficient flow to the lower body.

Sustained Total All-Region (STAR) Perfusion: An Optimized Perfusion Strategy for Norwood Reconstruction.

Early iterations of the Norwood procedure used aortic cross-clamping, myocardial arrest, and, sometimes, deep hypothermic circulatory arrest. The resulting hypothermia and prolonged ischemia caused frequent cardiac, neurologic, renal, and other end-organ dysfunctions. Our group describes a novel technique, sustained total all-region (STAR) perfusion, which circumvents these issues by providing continuous perfusion to the head, heart, and coronaries at temperatures of 32-34°C. A single DLP® straight venous cannula (Medtronic, Minneapolis, MN) is placed in the right atrium, and a DLP® pediatric arterial cannula, with a high-flow stopcock attached, is placed in the ascending aorta or innominate artery to provide flow to the head. A cardioplegia needle with walrus tubing is connected to the stopcock to provide flow to the coronary arteries. For lower body perfusion, an olive tip cannula is placed into the descending aorta lumen and attached to the 1/8″ line from the cardioplegia system which provides warm arterial blood flow. STAR perfusion allows the Norwood procedure to be completed with mild hypothermia and continuous perfusion to all vascular beds with reduced cardiopulmonary bypass as well as total operative times. This technique is successfully achieved with minimal changes to circuitry, minor modifications to heart-lung machine servoregulation and few additional cannulation disposables.

Reduction in blood transfusion in a cohort of infants having cardiac surgery with cardiopulmonary bypass after instituting a goal-directed transfusion policy.

BACKGROUND: Current trends in pediatric cardiac surgery and anesthesiology include goal-directed allogeneic blood transfusion, but few studies address the transfusion of platelets and cryoprecipitate. We report a quality improvement initiative to reduce the transfusion of platelets and cryoprecipitate in infants having cardiac surgery with cardiopulmonary bypass (CPB). METHODS: Data from 50 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB were prospectively collected after the institution of a policy to obtain each patient's platelet and fibrinogen levels during the rewarming phase of CPB. Data from 48 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB prior to the implementation of the policy change were retrospectively collected. Demographics, laboratory values and blood product transfusion data were compared between the groups, using the Chi-square/Fisher's exact test or the T-Test/Wilcoxon Rank-Sum test, as appropriate. RESULTS: The results showed more total blood product exposures in the control group during the time from bypass through the first twenty-four post-operative hours (median of 2 units versus 1 unit in study group, p=0.012). During the time period from CPB separation through the first post-operative day, 67% of patients in the control group received cryoprecipitate compared to 32% in the study group (p=0.0006). There was no difference in platelet exposures between the groups. CONCLUSION: Checking laboratory results during the rewarming phase of CPB reduced cryoprecipitate transfusion by 50%. This reproducible strategy avoids empiric and potentially unnecessary transfusion in this vulnerable population.

Predictors of electrocerebral inactivity with deep hypothermia.

OBJECTIVE: Cooling to electrocerebral inactivity (ECI) by electroencephalography (EEG) remains the gold standard to maximize cerebral and systemic organ protection during deep hypothermic circulatory arrest (DHCA). We sought to determine predictors of ECI to help guide cooling protocols when EEG monitoring is unavailable. METHODS: Between July 2005 and July 2011, 396 patients underwent thoracic aortic operation with DHCA; EEG monitoring was used in 325 (82%) of these patients to guide the cooling strategy, and constituted the study cohort. Electroencephalographic monitoring was used for all elective cases and, when available, for nonelective cases. Multivariable linear regression was used to assess predictors of the nasopharyngeal temperature and cooling time required to achieve ECI. RESULTS: Cooling to a nasopharyngeal temperature of 12.7°C or for a duration of 97 minutes was required to achieve ECI in >95% of patients. Only 7% and 11% of patients achieved ECI by 18°C or 50 minutes of cooling, respectively. No independent predictors of nasopharyngeal temperature at ECI were identified. Independent predictors of cooling time included body surface area (18 minutes/m(2)), white race (7 minutes), and starting nasopharyngeal temperature (3 minutes/°C). Low complication rates were observed (ischemic stroke, 1.5%; permanent paraparesis/paraplegia, 1.5%; new-onset dialysis, 2.2%; and 30-day/in-hospital mortality, 4.3%). CONCLUSIONS: Cooling to a nasopharyngeal temperature of 12.7°C or for a duration of 97 minutes achieved ECI in >95% of patients in our study population. However, patient-specific factors were poorly predictive of the temperature or cooling time required to achieve ECI, necessitating EEG monitoring for precise ECI detection.

Venous line filtration: a novel technique for cases involving inferior vena caval and right atrial tumor and associated thrombus: a two-case series.

Two patients are presented with right atrial tumors, who were considered to be at risk for tumor thrombus migration down the venous line into the cardiopulmonary bypass (CPB) circuit during surgical excision, which may lead to compromised or interrupted venous drainage. An arterial line filter was placed in the venous line to capture any material that might become dislodged and embolize into the circuit. Vacuum-assisted venous drainage, at approximately -50 mmHg, was used to overcome any resistance caused by the filter in the venous line. In one case, tumor thrombus obstructed the filter, requiring the use of the bypass line around the filter, so venous return could be maintained. In both cases, thrombus was found in the filter. The first case was a 44-year-old female (81 kg, 137 cm, body surface area (BSA) 1.66 m2) who presented with a metastatic pheochromocytoma with associated thrombus arising from the left adrenal gland and extending into the inferior vena cava (IVC) and right atrium. The second case was a 37-year-old male (95 kg, 178 cm, BSA 2.17 m2), who presented with a very large angiosarcoma tumor involving almost the entire right atrium. We have shown that venous line filtration with vacuum-assisted venous drainage can be performed safely, and should be considered in cases where there is tumor thrombus in the vena cava or right atrium, which may threaten venous return.